Testing database applications, including test data generation to ensure correctness
of queries, and checking for serializablity of applications running under
weak levels of consistency. For more details, look
here

Keyword querying in databases
Soumen Chakrabarti and I lead the
BANKS project,
which aims at supporting keyword queries on relational and
XML databases.

Earlier areas included and Main Memory Databases
(I was one of the founders of the DataBlitz main memory database
project in Bell Laboratories, Murray Hill).
I also worked on failure recovery
error checking and fault tolerance issues, particularly in
main memory databases.